2G Stock 2G bottom end safe limit with good tuning?

[beegeezy]

I have read that somewhere around 400 awhp is potentially safe for the stock 2G bottom end (obviously this depends on the tune, no knocking, general condition of the engine, etc.). I don't want to ask what turbo to use with my stock 2G block or the max awhp it will hold...but I do want to know what power range has been proven, given everything else is right (tune, fueling, etc.), to be safe long-term. I don't want to break any rods, pistons, or stock block records. I also am not looking at racing, mostly just street driving with some occasional pulls to redline for fun.

So, what has been a safe level of awhp (above stock) for thousands of miles of use? I would be running E85 also if that matters.

I would like to know if you have run a stock 2G bottom end, long-term, with 300+awhp or know of someone who has done this and not gone kaboom. Thanks!

 

[Kryndon]

Most of us who have AWDs love our torque down low to get the best off-the-line experience and performance. That tends to require a lot of timing advance under 4-5000 RPM which is where the stock rods tend to bend and break the most. What I'm trying to say is, you can get a 'safe' 300 awhp on a stock 7 bolt but you might also be able to get close to 400 awhp on the same setup if you tuned for it. Meaning, purposefully gimp your motor down-low so it doesn't experience as much torque and power until it reaches the RPMs where the torque exerted upon those rod angles aren't as impactful so you can optimize timing advance and AFRs/boost at that point.

This is just one piece of the puzzle. I'm sure the others will chime in with the rest. P.S, Mitsu sort of upgraded the 7 bolt rods from 2001 in their Evo 7 and up engines where they added a bit more reinforcement and ribbing on the rod. Those were the rods I put in my engine and it still goes strong to this day, abou 380 hp at the crank and 25 psi of boost.

 

[IHeartMyHonda]

Evo3 16g. E85, fuel pump, injectors. Exhaust, downpipe, and intercooler. Mild clutch.

You can make 375 all day and have a car that's tons of fun to drive and dead reliable if you don't launch it like a rally driver.

 

[beegeezy]

Evo3 16g. E85, fuel pump, injectors. Exhaust, downpipe, and intercooler. Mild clutch.

You can make 375 all day and have a car that's tons of fun to drive and dead reliable if you don't launch it like a rally driver.

I'm AWD and auto, so 375 hp at the wheels for me is probably a lot more at the flywheel vs you. But still, thanks for chiming in. How long have you been at that level?

 

[Justin DuBois]

400+ at the wheel - E85 using 1G rods and 2G pistons.

 

[jdxnc]

You're better off to run a slightly larger turbo that hits full boost a little later on rather than a smallish turbo like a 16g that lights right up. The stock 7 bolts weak point is the smaller rods which is torque that kills.

400ish is safe with a solid tune, more can be achieved if you're careful/lucky/good. 550+ has been done but for how long? Who knows.

 

[beegeezy]

You're better off to run a slightly larger turbo that hits full boost a little later on rather than a smallish turbo like a 16g that lights right up. The stock 7 bolts weak point is the smaller rods which is torque that kills.

400ish is safe with a solid tune, more can be achieved if you're careful/lucky/good. 550+ has been done but for how long? Who knows.

I have an HE341 that I’m hoping to use (I meant to buy an HY35, but that’s another story). It should spool around what a 20G does. I know that isn’t a big turbo, but it’s bigger than a 16G at least.

 

[jed344]

Keeping the TQ low early is critical. Lot's of years ago my own car lived at mid 20's for boost and soft timing with just hx35 7 blade in bep .55 housing with hks 272's and arp studs. I then sold the turbo set up and cam's to a local guy who i then tuned his car. We made 449whp on a 90 deg day at car show at 30psi and soft timing on his stock 7 bolt lower end too. I later turned the car up even more. He over heated the motor but when we tore it apart we could see the rod's were just about to let go. So his motor took mid 400whp+ for over a year but was just about to let go after we turned it up more.

Hy35 7 bolt we hurt after a year at high 20's for boost.

FP green car took a year of 30 psi too before it let go.

These where all on e85 and over the year's learned that tq early is the problem. Have to keep timing soft and either use a BCS to creep duty in or larger charger so it does not make a lot of tq early.

Now days i am fairly confident to run low 400's on a stock lower end as long as i can keep the tq low. I still warn that above 400whp i cannot guarantee how long it will live. I would guess we have got close to 500whp with the local car that got hot as during that pass i had the car at 33psi and knock sensor off with i think 16 degrees up top. That pass we had the car on c16 so even as it got so hot it warped the head it did not detonate.

Moral of story, TQ low early and good fuel with a good tuner. Just because it want's and can take the timing earlier you cannot put that in as the stock rods will say bye.

I think last few i tuned around the 400 mark with hx35 and larger set ups i would push threw peak tq at 3-5 degrees and only ramp up to 13-14 up top. Easier on the motor to make the power with boost then timing if you have the air.

 

[beegeezy]

Thank you, that’s very helpful info! It sounds like I have an appropriately sized turbo and goal. I am hoping to install the holset at low boost (10-15 psi) while I work on getting the fueling and intercooler dialed in. I am thinking of trying an air-to-water intercooler from a ford 6.7 powerstroke, as they are cheap and plentiful. I also want to build a diy killer chiller to cool the water and monitor the air intake temps, though I’ve heard E85 can handle warmer intake air.

I think this gives me confidence to push forward with aiming for 350-400 awhp when properly tuned. I have a set of K1 rods and wiseco pistons that can be used to strengthen the bottom end, but I’d be very happy for a long time with meeting my current power goals. I can then focus on making the car lighter and improving the brakes and suspension more.

 

[Justin DuBois]

I think this gives me confidence to push forward with aiming for 350-400 awhp when properly tuned. I have a set of K1 rods and wiseco pistons that can be used to strengthen the bottom end, but I’d be very happy for a long time with meeting my current power goals. I can then focus on making the car lighter and improving the brakes and suspension more.

These cars are difficult to reduce weight in a meaningful way. Sure - go for lighter un-sprung weight, wheels, bakes, suspension components etc.. but the chassis is a beast. If you are not in a competition, save the integrity of the car, and work on reliability, and power - and give yourself something you enjoy driving, instead of a stripped out tin can.

 

[IHeartMyHonda]

I'm AWD and auto, so 375 hp at the wheels for me is probably a lot more at the flywheel vs you. But still, thanks for chiming in. How long have you been at that level?

I had that setup for about 2 years, which for me was about 1200 miles. It's a weekend car, but I'd say 90% of those miles were abusive. I only removed the 16g to go with a hx35.

 

[beegeezy]

These cars are difficult to reduce weight in a meaningful way. Sure - go for lighter un-sprung weight, wheels, bakes, suspension components etc.. but the chassis is a beast. If you are not in a competition, save the integrity of the car, and work on reliability, and power - and give yourself something you enjoy driving, instead of a stripped out tin can.

Agreed, I was thinking wheels, brakes, coilovers, seats, ABS delete (not working currently anyways), and maybe a carbon fiber hood. I already have a small Braille battery to use. I'm keeping a/c, power steering, and not stripping the interior. Lighter and functional while making improvements over the original equipment is my gameplan.

 

[beegeezy]

400+ at the wheel - E85 using 1G rods and 2G pistons.

Also, I wanted to ask about this setup. I have to pull my head to replace the had gasket and I am also removing my oil pump for a BSE, inspection, and straight cut gears install. This would be a good time to pull the pistons and rods too since I'll have the top end and oil pan off. I was thinking of picking up some stock 6 bolt rods and having them machined for my 7 bolt crank and 2G pistons, and resized with some ARP bolts. I wonder if this isn't too expensive? I wouldn't have to pull the block to do this. I know a lot of people think to just jump to a full rebuild, but this would be less expensive than a full rebuild and less time for me. Also, even being machined to fit, 2G pistons with 6 bolt rods (and ARP bolts) are probably a decent amount stronger than my 7 bolt rods.

 

[dwb]

Also, I wanted to ask about this setup. I have to pull my head to replace the had gasket and I am also removing my oil pump for a BSE, inspection, and straight cut gears install. This would be a good time to pull the pistons and rods too since I'll have the top end and oil pan off. I was thinking of picking up some stock 6 bolt rods and having them machined for my 7 bolt crank and 2G pistons, and resized with some ARP bolts. I wonder if this isn't too expensive? I wouldn't have to pull the block to do this. I know a lot of people think to just jump to a full rebuild, but this would be less expensive than a full rebuild and less time for me. Also, even being machined to fit, 2G pistons with 6 bolt rods (and ARP bolts) are probably a decent amount stronger than my 7 bolt rods.

I think I paid about $350 a few years ago to have my 6bolt rods machined and fit to 2g pistons. The machinist implied he wouldn't do it again for that cost. Not to mention how much time I spent trying to locate a machine shop that would do this work.
Unless you already have big rods, and know a machinist, it might be more cost effective to just buy aftermarket rods.

 

[Justin DuBois]

Also, I wanted to ask about this setup. I have to pull my head to replace the had gasket and I am also removing my oil pump for a BSE, inspection, and straight cut gears install. This would be a good time to pull the pistons and rods too since I'll have the top end and oil pan off. I was thinking of picking up some stock 6 bolt rods and having them machined for my 7 bolt crank and 2G pistons, and resized with some ARP bolts. I wonder if this isn't too expensive? I wouldn't have to pull the block to do this. I know a lot of people think to just jump to a full rebuild, but this would be less expensive than a full rebuild and less time for me. Also, even being machined to fit, 2G pistons with 6 bolt rods (and ARP bolts) are probably a decent amount stronger than my 7 bolt rods.

It depends. I don't know what it takes to run 1G rods on a 7-bolt crank (not a combo I'm familiar with) If you have a 6-bolt rebuild, and you are looking to increase compression with 2G stock or forged pistons, the work to modify the 1G rod for the 2G pin isn't a huge ask - but it is machine shop time. I would look at the cost difference between modifying OEM parts vs after market parts before making a decision.

I know you have a 7-Bolt - but I thought its worth mentioning that the other strength you gain with a 1G 6-Bolt is the bigger head studs.

 

[dwb]

It depends. I don't know what it takes to run 1G rods on a 7-bolt crank (not a combo I'm familiar with) If you have a 6-bolt rebuild, and you are looking to increase compression with 2G stock or forged pistons, the work to modify the 1G rod for the 2G pin isn't a huge ask - but it is machine shop time. I would look at the cost difference between modifying OEM parts vs after market parts before making a decision.

I know the OP has a 7-Bolt - but I thought is worth mentioning that the other strength you gain with a 1G 6-Bolt is the bigger head studs.

Good call on the 7-bolt crank. I think there might be some issues that require machine work to the crank.

 

[beegeezy]

From what I’ve read the big end of the 6 bolt rods just needs to be slimmed down to match the 7 bolt rods (I think I’ve read 2mm) to fit the 7 bolt crank. I don’t think I can run aftermarket rods with the stock 2G pistons or I’d do that since I have some K1 h-beams already. But I won’t mess with it if it’s cost prohibitive.

 

[pauleyman]

From what I’ve read the big end of the 6 bolt rods just needs to be slimmed down to match the 7 bolt rods (I think I’ve read 2mm) to fit the 7 bolt crank. I don’t think I can run aftermarket rods with the stock 2G pistons or I’d do that since I have some K1 h-beams already. But I won’t mess with it if it’s cost prohibitive.

Why couldn't you run k1 rods with stock 2g pistons? Actually instead of spending money on machining why not buy new pistons and you're all set. You have everything you need.

 

[IHeartMyHonda]

Evo 8/9 pistons and rods swap directly into a 2g block. They're stronger than the 7 bolt parts and can be picked up used for pretty cheap. It's a great alternative for someone who doesn't want to go whole hog building a forged engine.

 

[beegeezy]

Why couldn't you run k1 rods with stock 2g pistons? Actually instead of spending money on machining why not buy new pistons and you're all set. You have everything you need.

I didn't think that was an option since the stock pistons are press fit and the K1 rods are for full-floating pistons. I have a new set of wiseco pistons but they are 85.5 mm overbore. I assumed if I was replacing the pistons, even with stock size units, I needed to at least hone the cylinders. I am hoping to find a middle ground where I don't have to pull the block for a full rebuild, mostly due to time constraints.

Evo 8/9 pistons and rods swap directly into a 2g block. They're stronger than the 7 bolt parts and can be picked up used for pretty cheap. It's a great alternative for someone who doesn't want to go whole hog building a forged engine.

I have read conflicting reports on evo pistons and rods. The evo guys bend the rods at similar power levels to stock 2G rods and the pistons are no better.

 

[jdxnc]

The Evo rods are no bigger than the 2g rods, MAYBE the metal is better? Who knows. They do have a slightly higher compression piston though.

 

[CrackedDSM]

Evo pistons in a DSM 4G63 actually end up being slightly less compression than the 2G DSM pistons due to cylinder head differences. Like 8.3:1 IIRC.